        function IsPC(){
        var userAgentInfo =  navigator.userAgent;
        var reg = new RegExp("(Android|iPhone|SymbianOS|Windows Phone|iPad|iPod)","ig");
        var isPC =  !reg.test(userAgentInfo);
        return isPC
        }
        var initFontSize=function(){
        var n=document.getElementsByTagName("html")[0],
            e=document.documentElement.clientWidth;
        if(IsPC()){
            if(e>750){
                n.style.fontSize = "100px"
            }else{
                n.style.fontSize = e/750*100+"px"
            }
        }else{
            n.style.fontSize=e/750*100+"px";
        }
        };
        initFontSize();
        window.onresize=function(){
        initFontSize()
        };